9,255 research outputs found
Data mining and accelerated electronic structure theory as a tool in the search for new functional materials
Data mining is a recognized predictive tool in a variety of areas ranging
from bioinformatics and drug design to crystal structure prediction. In the
present study, an electronic structure implementation has been combined with
structural data from the Inorganic Crystal Structure Database to generate
results for highly accelerated electronic structure calculations of about
22,000 inorganic compounds. It is shown how data mining algorithms employed on
the database can identify new functional materials with desired materials
properties, resulting in a prediction of 136 novel materials with potential for
use as detector materials for ionizing radiation. The methodology behind the
automatized ab-initio approach is presented, results are tabulated and a
version of the complete database is made available at the internet web site
http://gurka.fysik.uu.se/ESP/ (Ref.1).Comment: Project homepage: http://gurka.fysik.uu.se/ESP
Ferromagnetic materials in the zinc-blende structure
New materials are currently sought for use in spintronics applications.
Ferromagnetic materials with half metallic properties are valuable in this
respect. Here we present the electronic structure and magnetic properties of
binary compounds consisting of 3d transition metals and group V elements viz.
P, Sb and As in the zinc-blende structure. We demonstrate that compounds of V,
Cr and Mn show half metallic behavior for appropriate lattice constants.
By comparing the total energies in the ferromagnetic and antiferromagnetic
structures, we have ascertained that the ferromagnetic phase is stable over the
antiferromagnetic one. Of the different compounds studied, the Cr based systems
exhibit the strongest interatomic exchange interactions, and are hence
predicted to have the highest critical temperatures. Also, we predict that VAs
under certain growth conditions should be a semiconducting ferromagnet.
Moreover, critical temperatures of selected half metallic compounds have been
estimated from mean field theory and Monte Carlo simulations using parameters
obtained from a {\it ab-initio} non-collinear, tight binding linearized
muffin-tin orbital method. From a simple model, we calculate the reflectance
from an ideal MnAs/InAs interface considering the band structures of MnAs and
InAs. Finally we present results on the relative stabilities of MnAs and CrSb
compounds in the NiAs and zinc-blende structures, and suggest a parameter space
in substrate lattice spacings for when the zinc-blende structure is expected to
be stable.Comment: 7 pages, 6 figure
Charged Higgs bosons in Minimal Supersymmetry: Updated constraints and experimental prospects
We discuss the phenomenology of charged Higgs bosons in the MSSM with minimal
flavor violation. In addition to the constrained MSSM (CMSSM) with universal
soft supersymmetry breaking mass parameters at the GUT scale, we explore
non-universal Higgs mass models (NUHM) where this universality condition is
relaxed. To identify the allowed parameter space regions, we apply constraints
from direct searches, low energy observables, and cosmology. We find that
values of the charged Higgs mass as low as GeV can be
accommodated in the NUHM models, but that several flavor physics observables
disfavor large contributions, associated with high , quite
independently of MSSM scenario. We confront the constrained scenarios with the
discovery potentials reported by ATLAS and CMS, and find that the current
exclusion by indirect constraints is similar to the expected LHC discovery
reach with 30 fb of data. Finally, we evaluate the sensitivity of the
presented discovery potential to the choice of MSSM benchmark scenario. This
sensitivity is found to be higher in the case of a light ()
charged Higgs.Comment: 33 pages, 17 figures, v2: Minor revision, agrees with published
versio
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